Cumulative social risk and risk of death from cardiovascular diseases and all-causes.

Mortality rates for cardiovascular diseases (CVD) have declined steadily over the past few decades in high-income countries. This decline has by far disproportionately favored thosewith higher income, educational attainment, and social support or those who are members of ethnic majority groups [1–7]. Few studies have examined the cumulative effects of multiple social risk factors on CVD mortality rates [8]. Disparate exposure to multiple social risk factors may contribute to social inequalities in CVD mortality rates. We used data on 10,035 adults (age ≥ 30 years) with no history of CVD, from the NHANES III Mortality Study (1988–1994 survey data linked to 2006mortality data), to assess the prospective association between cumulative social risk and CVD deaths, b65-year-old mortality, and all-cause mortality. Linkage with the National Death Index allowed definition of CVD deaths as ICD-9 codes 390–459 or ICD-10 codes I00-I99. Income was assessed using the poverty income ratio (ratio of family income to the federal poverty level) dichotomized into below 1.00 (below the official definition of poverty) vs. 1.00 or greater (income above the poverty level). Education level was dichotomized into low (b12 years, representing b high school diploma) vs. high (≥12 years, representing high school diploma, some college, or college degree) levels. Self-reported race/ethnicity was classified into a minority group (nonHispanic Black, Mexican-American and Other) vs. non-Hispanic White. Single-living status (proxy for social isolation/low level of social support) was classified into two groups, married/living as married vs. never married, widowed, divorced, or separated. Each of the four social risk factors were assigned a score of 1 for their presence or 0 for absence and were summed to create a cumulative social risk score (range 0 to 4). Cox proportional models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for the association between cumulative social risk and mortality. We evaluated the contribution of biological risk factors (bodymass index [BMI], HbA1c, systolic blood pressure [SBP], cholesterol, triglycerides, C-reactive protein [CRP] and estimated glomerular filtration rate [eGFR]) to the association between cumulative social risk and CVD deaths. We hypothesized that these biological factors are on the pathway in the association between exposure to social risk factors and occurrence of CVD deaths, and thus are mediators of this association. HbA1c wasmeasured using a Bio-Rad Diamant ion exchange high-performance liquid chromatography system. Serum total cholesterol and triglycerides were measured enzymatically by a Hitachi 704 Analyzer. eGFR was based on the Modification of Diet in Renal Disease study equation. Serum CRP was measured using the Behring latexenhanced CRP assay. A total of 31.7% of adults reported at least one social risk factor; 7.1% reported 3 or more. Over a median 14-year follow-up, there were 2604 deaths (1386 inmales and 1218 in females) including 924 deaths related to cardiovascular diseases. Table 1 shows the age-and sex-adjusted associations of each social risk factorwithCVDdeaths, b65-year-oldmortality, and all-cause mortality. Hazard ratios for CVD deaths, b65-year-old mortality and all-cause mortality significantly increased with an increasing number of social risk factors and were greatest in those exposed to 3 or more social risk factors compared with those with 0 (Table 1). Table 2 shows the association between exposure to 3 or more social risk factors and CVD deaths, as well as the contribution of biological risk factors to this association. Biological risk factors accounted for 12% (95% CI: 4% to 18%) of the association between exposure to 3 or more social risk factors and CVD deaths. Previous studies on social inequalities in CVDmortality have typically operationalized social disadvantage using single measures of socioeconomic status (e.g.manual occupational class, low education level, low income) or a composite of socioeconomic measures in several periods through the life course [8]. However, summing the number of times an individual had been in a lower socioeconomic category as a proxy for cumulative social disadvantage, may erroneously attribute CVD mortality to risks associated with the accumulation of only socioeconomic International Journal of Cardiology 177 (2014) 1106–1107